The present disclosure relates generally to a junction barrier Schottky diode (JBS) and, more specifically, to a junction barrier Schottky diode with higher reverse blocking voltage.
Integrated circuits have generally included Schottky diodes for power applications. Schottky diodes tend to be very leaky at high reverse bias and high temperatures. Circuit designers have used junction barrier Schottky diodes to provide a solution to the leaky Schottky diodes. This combination provides a Schottky-like forward conduction and PN diode like reverse blocking of voltage. It basically includes a PN junction and a Schottky junction diode in parallel Although this has solved the leakage problems, the JBS diodes built to date have historically had reverse blocking voltages in the range of 30 volts. There is a need to provide an improved JBS diode with substantially greater reverse blocking voltage.
The present junction barrier Schottky diode has an N-type well having a surface and a first peak impurity concentration along a vertical axis; a P-type anode region in the surface of the well, and having a second peak impurity concentration along a vertical axis; an N-type cathode contact region in the surface of the well and laterally spaced from a first wall of the anode region, and having a third peak impurity concentration along a vertical axis; and a first N-type region in the surface of the well and laterally spaced from a second wall of the anode region, and having a fourth peak impurity concentration along a vertical axis. The center of the spaced region between the first N-type region and the second wall of the anode region has a fifth peak impurity concentration along a horizontal axis. An ohmic contact is made to the anode region and the cathode contact region, and a Schottky contact is made to the first N-type region, the spaced region and the well. The first and fifth peak impurity concentrations are less than the fourth peak impurity concentration, and the fourth peak impurity concentration is less than the second and third peak impurity concentrations.
The second peak impurity concentration may be less than the third peak impurity concentration. The spaced region may be the well and the first and fifth peak impurity concentrations are equal. The fifth peak impurity concentration may be less than the first peak impurity concentration, and the fifth peak impurity concentration in the spaced region results from overlap of the anode and the first N-type regions.
The cathode contact, anode and first N-type regions may have substantially the same depth. The cathode contact, anode and first N-type regions may be concentric. One of the cathode contact, anode and first N-type regions may be between two spaced anode or first N-type regions, cathode contact or first N-type regions, and the cathode contact or anode regions respectively may be between two spaced cathode contact regions.
The maximum impurity concentration of the anode and/or the first N-type regions may be below the surface.
Although the junction barrier Schottky diode is generally used in integrated circuits, the present junction barrier Schottky diode may be a discrete device.
These and other aspects of the present disclosure will become apparent from the following detailed description of the disclosure, when considered in conjunction with accompanying drawings.